Graphene has high charge carrier mobilities and can be used to fabricate graphene based field effect transistors (FET). The transistor may have a locally gated (top-gate) electrode on the graphene and may be useful for operating at low power and terahertz frequencies applications, including low noise amplifiers and electromechanical resonators. Ideal dielectric barriers separating the top-gate from the graphene should be thin, free of pinholes, and have uniform thickness.
Construction of a top-gated electrode can be difficult due to the incompatibilities of graphene with typical high dielectric constant (high-κ) barrier preparations. Pristine graphene has few functional groups, which hinders the modification of the surface with precursors commonly used for atomic layer deposition (ALD). The inability to modify the surface with precursors results in non-uniform films that nucleate primarily at the edges and defects of the graphene. Using physical vapor deposition to produce the dielectric film may damage the graphene, and functionalization of the graphene with ozone and/or nitrous oxide may result in non-uniform films or degraded carrier mobilities of the graphene field effect transistor.